The invention relates to a current-discrimination arrangement having an input for receiving a current to be discriminated and an output.
Such a current-discrimination arrangement may be used inter alia in current stabilizers but also in, for example, signal-level detectors.
In current stabilizers of the so-called "band-gap reference" type, as described inter alia in U.S. Pat. No. 3,887,863, such a current discrimination arrangement comprises two current paths, a semiconductor junction in one path being shunted by a semiconductor junction connected in series with a resistor in the other path. The currents in the two paths are compared by means of a resistor and a differential amplifier or by means of a current mirror--which comparison constitutes the discrimination function--and are controlled in such a way that the current densities in the two semiconductor junctions are in a ratio of 1:n, which factor n.noteq.1 if the two semiconductor junctions are unequal or if the currents in the two paths are made unequal. The current is then stabilized at a value equal to (KT/qR) 1n n, where K is Boltzmann's constant, T the absolute temperature in .degree.K., q the elementary charge, R the value of said resistor, and ln n the natural logarithm of the factor n. In this type of stabilizer the current is stabilized at a value determined by the factor n. The steepness of the current discrmination is also determined by the factor n. The stabilization improves as the factor n deviates further from unity, but the circuit arrangement then becomes more asymmetrical, which is generally a disadvantage.